Tiltable truck cabs, particularly those which are fully suspended relative to the truck frames, have a tendency to cock (that is, to swing "out of true") during tilting because of uneven loading on the tilt cylinders as a result of uneven cab weight distribution. To cure this defect, an anti-roll bar (also called a torsion bar) is usually fitted between the left- and right-hand pivots. However, such anti-roll bars interfere with the desirable spring rates of the cab in their over-the-road position.